The cashew (Anacardium occidentale L.) is native to tropical America. Originating from Brazil, it has become naturalized in many tropical countries such as Vietnam, India, Nigeria, Tanzania, Ivory Coast, Mozambique, and Benin. Cashew is formed by the developed peduncle (apple) attached to the nut (actual fruit composed of shell + kernel).
The peduncle, which is also called the pseudo-fruit, false fruit, cashew apple, or simply cashew, represents the edible portion, in natura and also as juices, pulp, and preserves .
Apart from the usual presence of sugars and organic acids, one important characteristic of cashew apple is its high vitamin C content, four times higher than that of sweet orange (Rufino et al. 2010; Akinwale 2000).
Cashew apple is the peduncle of the cashew fruit, which is rich in reducing sugars (fructose and glucose), vitamins, minerals, and some amino acids. Although cashew apples can be consumed as juice, ice cream, and other foodstuffs, cashew tree cultivation is an agricultural activity directed at the production of cashew nut.
The nuts represent only 10% of the total fruit weight, and large amounts of cashew apples are lost in the field after nut removal. The expected yield for the cashew tree under rainy conditions is approximately 1 t/ha of raw cashew nut and 10 t/ha of cashew apple. Under irrigated conditions, it may reach 3.8 t/ha of raw cashew nut and 30 t/ha of cashew apple (Rabelo et al. 2009).
The average yield of juice extraction is approximately 85% (v/w), thus the juice productivity can reach 25.5 m3/ha. The amount of sugar in cashew apples depends on the cultivar. Naragaraja et al. (2007) reported sugar contents from 50 to 200 g/L. Thus, sugar productivities may reach up to 5 t/ha. According to government data (National Agriculture Research Agency–EMBRAPA/CNP.
Variations in the mineral, phenol, tannin, vitamin C, and sugar composition of Ghana’s cashew apple juice were investigated by Lowor and Agyent-Badu (2009). The mean proximate composition was as follows: phenolics (0.27% p/v), condensed tannins (0.27% p/v), vitamin C (231.4 mg/100 mL), and sugars (12.05 g/L).
The mineral composition (mg/100 mL) showed potassium (76.0) to be the highest, followed by calcium (43.0), magnesium (10.92), phosphorous (0.79), and sodium (0.41). Zinc, copper, and iron concentrations were much lower and ranged from 0.05 to 0.08 mg/100 mL.
Fermentation is a traditional way of preserving foods. Since ancient times, even without knowing that microorganisms were responsible for the food transformation, fermented foods have been used for human feed and nutrition.
In general, fermentation stabilizes food by making it so acid (low pH) or alcoholic that undesirable microorganisms find it difficult to grow. Fermented products are often further protected from oxidation and infection by microorganisms using air-tight containers or heat.
The word fermentation typically refers to the fermentation of sugar to alcohol using yeast in microaerobic or anaerobic conditions. However, nowadays, the term fermentation is widely applied even for processes that are not anaerobic, such as vinegar production.
Several foodstuffs are now produced using microorganisms such as bakery products, yogurts, fermented milks, wines, beer, sausages, fish, fermented soy, fermented beans, and sauerkraut among many others. Because of the large availability of cashew apples as a cashew nut by-product, cashew apple juice has been studied as a substrate for biotechnological process. In , some applications of cashew apple juice in fermentative and enzymatic processes are presented.